The goal of this project is to analyze the mechanisms whereby antibody production at the cellular level is controlled. Specifically, we plan to study the inhibitory effects of various forms of antigens and immune complexes, anti-idiotypic antibodies and suppressor thymus-derived lymphocytes on the secretion of specific antibodies by differentiated antibody forming cells. A major emphasis will be placed on the use of mouse plasmacytomas which produce antibodies of defined specificities as model systems. Such tumor cells, being homogeneous populations, are readily amenable to detailed biochemical and morphologic analyses; moreover, several lines of evidence show that in spite of being neoplastic, they are susceptible to regulatory influences much like physiologic lymphocytes. A clearer understanding of the mechanisms that regulate antibody production is not only one of the central issues in immunobiology but is also of critical importance in devising regimens to control allergic and autoimmune disorders.